Furnace gas valve wont open (roll out switch failure)

My GMP075-3 will start and fire for about 1-2 minuites then the gas valve will close and the unit will not restart. When I test voltage accross the valve and it read 0. So I powered down the furnace reset all 4 roll out switches, turned the power back on and the gas valve opened and the furnace fired up. Again within 1-2 minuites the gas valve closed. I also disconnected all but one of the roll out switches and bypassed the rest and the same problem occured. I tried this with each of the 3 switches directly connected to the combustion box and every time it failed. Therefore I believe I am overheating the combustion box and tripping the roll out switches. Any ideas for the over heating?

I know it is failing to an overheating combustion box. The gas valve closes when one of the (4) the roll out switches trips due to high temperature in the combustion chamber. When I reset the switches the furnce will fire but only to trip one of the sensors again. I have also replaced the filter and cleaned the very dirty blower and it still fails. However it still seems like the blower is not blowing very much air (I just bought the home so I do not kow what the proper operation should be). Could it be overheating due to a bad blower or blower motor. I know it is failing to an overheating combustion box. The gas valve closes when one of the (4) the roll out switches trips due to high temperature in the combustion chamber. When I reset the switches the furnce will fire but only to trip one of the sensors again. I have also replaced the filter and cleaned the very dirty blower and it still fails. However it still seems like the blower is not blowing very much air (I just bought the home so I do not kow what the proper operation should be). Could it be overheating due to a bad blower or blower motor.

Not when it happens but if I try to restart with out resetting the roll out switches it will blink once, flame failureNot when it happens but if I try to restart with out resetting the roll out switches it will blink once, flame failure

I think the cracked heat exchanger is the answer. When the blower turns on the flame will roll back into the combustion chamber and also has orange tipped flames.I think the cracked heat exchanger is the answer. When the blower turns on the flame will roll back into the combustion chamber and also has orange tipped flames.

On a call for heat, the 24 volt thermostat sends a signal to the control module. The control module will indicate a call for heat with a light on the control either blinking or remain solid depending upon model. The inducer (exhaust) blower will purge all gasses from the furnace and pressurize a pressure switch. Once the pressure switch tells the module to continue, the electronic ignition will energize and send 120 volts to the ignitor. The ignitor will glow and you will be able to see it if viewed thru the small inspection port. Once the ignitor gets hot enough, it sends a signal to the module opening up the gas valve (24 volts). Either a pilot will come on or the burner tube will ignite then spread the flame to all burners. Lastly a safety sensor will be looking for a certain temperature within a few seconds and the furnace will continue to operate and the room air blower will turn on in a minute or two.

What could go wrong? The unit will not run if there is no signal from the thermostat (bad thermostat or broken wire), the control module does not sense a signal from the thermostat (bad control), the inducer does not energize (bad motor), the pressure switch does not close (blocked vent piping, bad switch, plugged condensate hose), the ignitor does not energize (bad control, bad ignitor), the gas valve does not open or there is no gas (bad gas valve, broken wire, no gas), the pilot does not lite (dirty pilot), the burner does not lite (bad burner, plugged orifice, not enough combustion air), the flame does not spread to each burner (bad flame spreader, dirty flame spreader, more bad burners), the flame safety sensor does not detect flame (dirty or bad flame spreader, bad flame sensor, broken wire, bad control), or the room air blower does not energize (bad fan motor, bad control).

Most newer furnaces will have a diagnostic center or control built into the control module. You may be able to view it as it is running thru a small viewing port. Some models will require the removal of an access panel prior to finding it. On the reverse of the access panel, there will be a diagnostic chart that will aide you in understanding any error code recorded (usually a blinking light).

your one blink indicates that the furnace is trying to ignite for a number of times without success. Follow the sequence of operation I sent you yesterday to help diagnose where it is failing.your one blink indicates that the furnace is trying to ignite for a number of times without success. Follow the sequence of operation I sent you yesterday to help diagnose where it is failing.

Yes, the blower motor may not be reaching a speed to push out the hot air. Does it make a difference if you run the system with the blower door open? Your blower has 4 speeds. Check to see what color wire is connected to the Heat terminal on the control board. If you have the red wire connected, change places with either the Orange (med-low) wire or the Red (Med) wire.

Another thing to look at is if all the return air dampers and supply registers and dampers if you have them are open. A restriction in air flow over the heat exchanger will cause this condition.

Go here for an operation manual for your furnace. http://ns3.dnmech.com/lit/IO-244c.pdfYes, the blower motor may not be reaching a speed to push out the hot air. Does it make a difference if you run the system with the blower door open? Your blower has 4 speeds. Check to see what color wire is connected to the Heat terminal on the control board. If you have the red wire connected, change places with either the Orange (med-low) wire or the Red (Med) wire.

Another thing to look at is if all the return air dampers and supply registers and dampers if you have them are open. A restriction in air flow over the heat exchanger will cause this condition.

One other possibility, cracked heat exchanger causing the room air blower to blow into the combustion chamber and force heat toward the spill switch. May be a good idea to look closely at the heat exchanger.One other possibility, cracked heat exchanger causing the room air blower to blow into the combustion chamber and force heat toward the spill switch. May be a good idea to look closely at the heat exchanger.

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TRI-COLOR (DSI LED) DIAGNOSTIC TABLE
No. of Red BLINKS
1 Flame sensed when no flame should be present
Verify the gas valve is operating and shutting down properly. Flame in burner assemble should extinguish promptly at the end of the cycle. Check orifices and gas pressure.

6 BLINKS 1st-stage pressure switch cycle lockout If the first stage pressure switch cycles 5 times (open, closed) during one call for heat from the thermostat the control will lockout.Check pressure switch for fluttering, inconsistent closure or poor vacuum pressure.
7 BLINKS External lockout (retries exceeded) Failure to sense flame is often caused by carbon deposits on the
flame sensor, a disconnected or shorted flame sensor lead or a
poorly grounded furnace. Carbon deposits can be cleaned with
emery cloth. Verify sensor is not contacting the burner and is locatedin a good position to sense flame. Check sensor lead for shortingand verify furnace is grounded properly.

8 BLINKS External lockout (ignition recycles
exceeded where flame is established and then lost)Check items for exceeded retries listed above and verify valve is not dropping out allowing flame to be established and then lost.

9 BLINKS Grounding or Reversed polarity Verify the control and furnace are properly grounded. Check and reverse polarity (primary) if incorrect.

i hope the heater doesnt come on when a limit switch is open,you really have problems. so a limit is telling you that your furnace it over heating. first check filter and heat vents and returns they must be clean and open. closing heat vent or blocked returns will cause over heating. after chacking this look at firing rate. furnace could be overfired. you would need a "u" gauge to check manifold pressure. your name plate will tell you what this should be. find the tap on the burner manifold or outlet of gas valve. fire furnace and see what it is. 3.5"wc for nat and 10" wc for propane maybe.

Problem: Your furnace will not ignite the gas to
produce heat for your home. When a furnace has a bad ignitor what I see most of
the time is the following sequence of operation:

1.
Thermostat calls for heat.
2.
Draft inducer motor starts.
3.
Pressure switch attached by a small plastic or rubber tube senses the
negative pressure produced by the draft inducer and
closes.
4.
Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small
metal probe about 1/8" in diameter, with a white
porcelain base) does not sense the flame, so after 8
to 10 seconds the hissing sounds stops with no
ignition of gas to heat your home. Your furnace shuts down and goes into a lock out condition until you turn your power switch back
off and on again. Then the sequence starts all over
again with no ignition of the gas.
Solution:You probably need to
purchase and install a new ignitor. I would suggest that you inspect your
ignitor closely for cracks. Make sure you do not
touch the ignitor with your bare hands. If you do not
visually see a crack, then you could have a furnace control board problem or a
limit, rollout switch problem. The furnace's control board
might not be supplying the voltage to the ignitor. If your furnace
lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then
you need to clean your flame sensor with light sand paper or steel wool. You
might need a new flame sensor, but most of the time they can be cleaned an will
work well after cleaning.

Hi, if you have replaced the control board and pressure switch, you need to check the sequence of operation. Starting with the inducer motor, must start up to pressurize unit box and be sure the pressure switch is closed. Even though you have replaced this switch, it may not have enough pressure to close it due to condensation in hose, a leak and so on. Jump across this switch to see if the pilot will light next. If this unit has a flame roll out switch located by the corner burner, make sure it is not tripped. Sequence of operation is, first your inducer motor will start and vent old gases and build pressure. Pressure switch will make and send signal to ignitor board to start pilot. If you have a HSI pilot, (Hot surface ignition ) it will glow. Next it gets the flame sensor hot enough to send a signal that the pilot is proved back to the board to fire the main gas smart valve with 24 volts. Go through this check as I have layed out. The flame sensor is right along side of the pilot tube and if the metal tip gets dirty, it will not fire. You can clean it with sanding cloth or fine steel wool to clean. If you go through all of these steps and it will not fire after you have made sure you have 24 volts ac at all controls in the sequence I have said, check the main gas valve across terminal C and MV for 24volts. If you have 24volts and it won't open the valve, it is faulty. Check this out for me and let me know. If no 24 volts, you have missed a safety in the sequence. Sincerely,Shastalaker7A/C, Heating& Refrigeration Contractor

could be a bad roll out switch a small thermal device located around the base of the burner ,locate on wirind diagram an ck with ohm meter should read closed , also could be to much gas presure if natural gas get the gas co. to check presure , also could be a faulty equipment ground from supply from breaker panel make sure well grounded and connections tight ,must have this gnd to keep gas valve open , hope some of these ideas help .

if it has a pilot, you can follow the pilot tube from the gas valve back to the burner assembly and find it. It may not have one and if this is the case, the air flow switch is supposed to close when the inducer fan comes on . If the flue is clogged, condensation in the bottom of inducer fan(would hear cracking). then after the draft safety switch is closed,the gas vavle will get 24 volts and allow the gas valve to open

Closed pressure switch can be from dirty combustion vents, bad chamber pressure - like missing screws, maladjusted gas pressure, failing pressure switch, loose hoses, moisture in the hoses or fan blades The switch need to be closed to ge the unit to work